A recent study published in the June issue of the American Journal of Clinical Nutrition shows that vitamin D-based nutrients help prevent cancerous cells from forming.

The study was conducted on 1179 community-dwelling women randomly selected from the population of healthy postmenopausal women aged >55 y in a 9-county rural area of Nebraska. The subjects received for more than 4 years a regular dose of 1400–1500 mg supplemental calcium/d alone (Ca-only), supplemental calcium plus 1100 IU vitamin D3/d (Ca + D), or placebo.

Researchers found that the vitamin D and Calcium combination helped lower the incidence of cancer in women who received it, compared to women who received placebo, indicating that improving calcium and vitamin D nutritional status substantially reduces all-cancer risk in postmenopausal women.

"Our study shows that with adequate vitamin D, cancer can be prevented -- or a high incidence of it can," said Joan Lappe, a professor of nursing and medicine at Creighton University and the lead author of the study.

"This is the first study that shows, in a clinical trial, that adequate levels of vitamin D can reduce the risk of cancer."

However, skeptics say the results of the research need to be taken with a grain of salt, since previous studies contradict the recent findings.

For example, a more intensive study conducted for a longer period by Dr. Jacques Rossouw and his team from the National Institutes of Health on the incidence of colorectal cancer in women population (colorectal cancer being the third leading cancer killer of US women) showed no positive effect whatsoever when administrating vitamin D. His group conducted a study that followed 36,282 postmenopausal women for seven years to test the effects of vitamin D on the aforementioned type of cancer.

"In our study we found absolutely no indication of an effect of calcium or vitamin D [on cancer] -- zero," he said. "And that's over a seven-year period. It was a much larger study and much a longer study."

Dr. John Milner, chief of the Nutrition Science Research Group at the National Cancer Institute, also agrees that some skepticism is necessary.

"We need to put this in the context of the entire diet and lifestyle and understand why we're getting some effect," Milner said. "I don't want to minimize it, but let's see a little bit more before we start jumping into public health policies."

Colorectal cancer is one of the most common cancers in the world. Every year, around one million people develop colorectal cancer worldwide.